Figure 1

Conventional drive systems for motorizing a manual wheelchair. (a) Dual-wheel drive system. It propels the two large wheels. When the left and right wheels rotate same direction, a wheelchair performs translational motion. When they rotate different direction with same velocities, a wheelchair performs pivot turn motion. (b) Single-wheel drive system. When a wheelchair performs translational motion, a drive wheel directs to the back and forth direction. When a wheelchair performs pivot turn motion, a drive wheel directs to the left and right direction. A user has to wait until the direction of it changes.